"Ted Cruz lies. He is a liar," Trump said in an appearance on MSNBC's Morning Joe. "That's why nobody likes him. That's why his Senate people won't endorse him. That's why he stands on the middle of the Senate floor and can't make a deal with anybody."

Cruz has famously made few friends during his tenure in Washington DC, a trait that Cruz himself highlights as a centerpiece of his pledge to fight the Washington "cartel."

But Trump, who takes pains to point out his "very good" relationships with Democrats and Republicans alike, said that even President Barack Obama - despised by the GOP - is more likable than the Texas senator.

"I think actually Ted is more strident than Obama, if you want to know the truth," he said. "Nobody gets along with Ted. At least some people like Obama. Nobody likes Ted."